The present invention relates to an image transmission system and techniques related thereto, and particularly to an image transmission system, an image pickup apparatus, an image pickup apparatus unit, a key generating apparatus, and a program usable for security service monitoring the inside of a house or an office.
Network technology has recently made remarkable progress, providing an environment that enables various information to be exchanged via networks. In such an environment, there is a monitoring system that has a camera installed inside a house or an office, and transmits video, a still image or the like from the camera via a network to thereby monitor remotely a state of the inside of the house or the office (see Patent Document 1, for example). Such a monitoring system has various uses for crime prevention in the house or the office, monitoring a pet where no person is present, checking a state of a senior citizen living alone in a remote place, and the like.    [Patent Document 1]
Japanese Patent Laid-Open No. 2002-183860
As the environment enabling various information to be exchanged via networks has been arranged as described above, a problem of ensuring security on the networks has been becoming manifest. That is, though various information can be easily exchanged via the networks, the information is always in danger of being intercepted by a malicious third party. The problem has recently been drawing much attention also from a viewpoint of protection of privacy, and it is urgently necessary to deal with the problem.
Among monitoring systems as described above, there is a system employed to ensure security by connecting a house or an office to a monitoring company by a special line. However, since the system using such a special line is very expensive, the system is employed only by some that can afford sufficient cost to ensure security, such as large companies, office buildings, museums or the like. Because of such a background, ordinary households have not yet come to readily use a monitoring system using a monitoring camera.
As a new monitoring system developed with the recent spread of portable terminals such as portable telephones and the like, there is a system of a virtual private network (VPN) configuration that connects a monitoring camera installed within a house with a portable terminal carried by a user while the user is out of the house by using a router or the like installed within the house. The VPN provides substantially the same effects as installing a special line, by providing an encryption processing function for both the transmitting side and the receiving side. However, while there is a desire to check the monitoring camera from a computer rather than a portable terminal, for example in cases where a state of the inside of a house is desired to be checked for a time during a break from work and where a state of the inside of a house is desired to be monitored at all times using a special monitor, it is not possible to connect to the VPN from a LAN (Local Area Network) within an office.